US2009092536A1PendingUtilityA1

Crystal production process using supercritical solvent, crystal growth apparatus, crystal and device

Assignee: UNIV TOHOKUPriority: Jul 1, 2005Filed: Jun 29, 2006Published: Apr 9, 2009
Est. expiryJul 1, 2025(expired)· nominal 20-yr term from priority
C30B 29/406C30B 7/10C30B 29/18C30B 29/16C30B 29/38Y10T117/1004
45
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Claims

Abstract

To control the precipitation position of a crystal and increase the yield of the crystal by performing the crystal growth according to the solvothermal method while allowing a predetermined amount of a substance differing in the critical density from the solvent to be present in the reaction vessel; and to prevent mixing of an impurity into the crystal and improve the crystal purity.

Claims

exact text as granted — not AI-modified
1 : A crystal production process comprising growing a crystal by using a solvent in the supercritical state and/or subcritical state and a raw material in a reaction vessel, wherein
 a substance (X) satisfying the following formula (1) and having a critical density difference of 25% or more from said solvent is allowed to be present in said reaction vessel, and   the precipitation position of the crystal is controlled by adjusting the amount of said substance (X):   
     
       
         
           
             
               
                 
                   
                     
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           raw 
                            
                           
                               
                           
                            
                           material 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           substance 
                            
                           
                               
                           
                            
                           
                             ( 
                             X 
                             ) 
                           
                         
                         ) 
                       
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           raw 
                            
                           
                               
                           
                            
                           material 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
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                           solvent 
                         
                         ) 
                       
                     
                     × 
                     100 
                   
                   ≤ 
                   20 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
   
   
       2 : A crystal production process comprising growing a crystal by using a solvent in the supercritical state and/or subcritical state and a raw material in a reaction vessel, wherein
 a substance (X) satisfying the following formula (1) and having a critical density difference of 25% or more from said solvent is allowed to be present in said reaction vessel, and   the amount of a reaction vessel-derived metal element contained in the grown crystal is controlled by adjusting the amount of said substance (X):   
     
       
         
           
             
               
                 
                   
                     
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           raw 
                            
                           
                               
                           
                            
                           material 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           substance 
                            
                           
                               
                           
                            
                           
                             ( 
                             X 
                             ) 
                           
                         
                         ) 
                       
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           raw 
                            
                           
                               
                           
                            
                           material 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           solvent 
                         
                         ) 
                       
                     
                     × 
                     100 
                   
                   ≤ 
                   20 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
   
   
       3 : The crystal production process according to  claim 1 , wherein the crystal is grown in said reaction vessel by further using a mineralizer satisfying the following formula (2): 
     
       
         
           
             
               
                 
                   
                     
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           mineralizer 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           substance 
                            
                           
                               
                           
                            
                           
                             ( 
                             X 
                             ) 
                           
                         
                         ) 
                       
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           mineralizer 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           solvent 
                         
                         ) 
                       
                     
                     × 
                     100 
                   
                   ≤ 
                   20 
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
   
   
       4 : The crystal production process according to  claim 1 , wherein said reaction vessel has an inlet tube at its upper part, the critical density of said substance (X) is smaller than the critical density of said solvent and during the crystal growth, said substance (X) is present in an amount of 1 time or more the volume of said inlet tube. 
   
   
       5 : The crystal production process according to  claim 1 , wherein said reaction vessel has an inlet tube at its lower part, the critical density of said substance (X) is larger than the critical density of said solvent and during the crystal growth, said substance (X) is present in an amount of 1 time or more the volume of said inlet tube. 
   
   
       6 : A crystal production process comprising growing a crystal by using a solvent in the supercritical state and/or subcritical state and a raw material in a reaction vessel with a part of the inner surface being formed of a non-noble metal, wherein
 a substance (X′) having a critical density difference of 25% or more from the solvent and substantially incapable of reacting with the reaction vessel is allowed to be present in the reaction vessel and during the crystal growth, the inner surface portion except for a noble metal is covered with the substance (X′).   
   
   
       7 : A crystal production process comprising growing a crystal by using a solvent in the supercritical state and/or subcritical state and a raw material in a reaction vessel with a part of the inner surface being formed of a non-noble metal, wherein
 the amount of a reaction vessel-derived metal element contained in the grown crystal is controlled by adjusting the amount of a substance (X′) having a critical density difference of 25% or more from the solvent and substantially incapable of reacting with the reaction vessel in the reaction vessel.   
   
   
       8 : The crystal production process as claimed in  claim 6 , wherein the crystal is grown in said reaction vessel by further using a mineralizer satisfying the following formula (3): 
     
       
         
           
             
               
                 
                   
                     
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           mineralizer 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           substance 
                            
                           
                               
                           
                            
                           
                             ( 
                             
                               X 
                               ′ 
                             
                             ) 
                           
                         
                         ) 
                       
                       
                         ( 
                         
                           solubility 
                            
                           
                               
                           
                            
                           of 
                            
                           
                               
                           
                            
                           mineralizer 
                            
                           
                               
                           
                            
                           in 
                            
                           
                               
                           
                            
                           solvent 
                         
                         ) 
                       
                     
                     × 
                     100 
                   
                   ≤ 
                   20 
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
   
   
       9 : The crystal production process according to  claim 6 , wherein said reaction vessel has an inner surface formed of a non-noble metal at its upper portion and the critical density of said substance (X′) is smaller than the critical density of said solvent. 
   
   
       10 : The crystal production process according to  claim 6 , wherein said reaction vessel has an inner surface formed of a non-noble metal at its lower portion and the critical density of said substance (X′) is larger than the critical density of said solvent. 
   
   
       11 : The crystal production process according to  claim 6 , wherein said reaction vessel has an inlet tube formed of a non-noble metal at its upper part, the critical density of said substance (X′) is smaller than the critical density of said solvent, said substance (X′) is a substance substantially incapable of reacting with said inlet tube and during the crystal growth, said substance (X′) is present in an amount of 1 time or more the volume of said inlet tube. 
   
   
       12 : The crystal production process according to  claim 6 , wherein said reaction vessel has an inlet tube formed of a non-noble metal at its lower part, the critical density of said substance (X′) is larger than the critical density of said solvent, said substance (X′) is a substance substantially incapable of reacting with said inlet tube and during the crystal growth, said substance (X′) is present in an amount of 1 time or more the volume of said inlet tube. 
   
   
       13 : The crystal production process according to  claim 1 , wherein said substance (X) or said substance (X′) is added to said reaction vessel. 
   
   
       14 : The crystal production process according to  claim 1 , wherein said substance (X) or said substance (X′) is selected from the group consisting of hydrogen, helium, nitrogen, chlorine and oxygen. 
   
   
       15 : The crystal production process according to  claim 1 , wherein the obtained crystal is a single crystal. 
   
   
       16 : The crystal production process according to  claim 1 , wherein the obtained crystal is any one of a nitride of a Periodic Table Group 13 element, ZnO and rock crystal. 
   
   
       17 : The crystal production process according to  claim 1 , wherein said solvent is a nitrogen-containing solvent. 
   
   
       18 : The crystal production process according to  claim 1 , wherein said solvent is water. 
   
   
       19 : The crystal production process according to  claim 4 , wherein said solvent is a nitrogen-containing solvent and said substance (X) or said substance (X′) is hydrogen and/or helium. 
   
   
       20 : The crystal production process according to  claim 5 , wherein said solvent is a nitrogen-containing solvent and said substance (X) or said substance (X′) is nitrogen and/or chlorine. 
   
   
       21 : The crystal production process according to  claim 4 , wherein said solvent is water and said substance (X) or said substance (X′) is hydrogen and/or helium. 
   
   
       22 : The crystal production process according to  claim 5 , wherein said solvent is water and said substance (X) or said substance (X′) is oxygen. 
   
   
       23 : The crystal production process according to  claim 3 , wherein said mineralizer is an acidic mineralizer. 
   
   
       24 : The crystal production process according to  claim 1 , wherein said reaction vessel is an autoclave. 
   
   
       25 : A crystal production apparatus using a solvent in the supercritical state and/or subcritical state, the apparatus comprising a metering mechanism for adding a substance differing in the critical density from said solvent at a predetermined ratio to a reaction vessel. 
   
   
       26 : The crystal production apparatus as claimed in  claim 25 , wherein the reaction vessel is an autoclave. 
   
   
       27 : A crystal comprising a nitride of a Periodic Table Group 13 element, produced by a crystal production process of growing a crystal by using a solvent in the supercritical state and/or subcritical state and a raw material in a reaction vessel, wherein the Cr content is 9×10 14  cm −3  or less and the Fe content is 9×10 16  cm −3  or less. 
   
   
       28 : The crystal as claimed in  claim 27 , wherein the Ni content is 5×10 16  cm −3  or less. 
   
   
       29 : The crystal as claimed in  claim 27 , wherein said nitride of a Periodic Table Group 13 element is gallium nitride. 
   
   
       30 : A device using the crystal claimed in  claim 29 .

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